Luminaire



April zl, 1942. T. w. ROLPH ETAL 2,280,l60

-April21, 1942. w, RQLPH ETAL 2,280,160

' LUMINAIRE Filed Oct. 10, 1940 v 3 Sheets-Sheet 2 ATTORNEY April 21, 1942. w. ROLPH Erm. 2,280,160

LUMINAIRE Filed Oct. 10, 1940 3 Sheets-Sheet 3 INVENTORS ATTORNEY Patented Apr. 21, 1942 UNITED STATES PA ENT oFFlcE LULIINAIRE Thomas W. Rolph and KurtFr-anck, Newark, Ohio, assignors to Holophane Company, Inc., New York, N.Y., a corporation of Delaware Application More 10, 1940, Serial No. 360,535

8 Claims.

The present invention relates luminaires and is more particularly directed toward luminaires adapted tor lighting displays occupyingelongated areas, such as counters in stores and for lightof the counter, the light beam is projected rearwardly at a slight angle to the vertical.

In accordance with the present invention the luminaire provides a fairly wide distribution lengthwise of the working area, or counter, so that the luminaires may be spaced along the ceiling over the working area to be lighted; and avoid the spotlight efiect obtained when the beams from adjacent units do not overlap.

According to the present invention this lighting result is obtained by employing the concentrated light source such as an incandescent lamp, and a two part lens systems, wherein the upper part is adapted to receive widely divergent rays from the source and converge them into a moderately divergent beam, andthe lower. part of the lens system is provided with prisms parallel with the area to be lighted and adapted to re- .ceive the moderately divergent; light and refract poses oiillustratlng the present invention, one

of the embodiments in which the invention may take form, it being understood that the drawings are illustrative of the invention-rather than limiting the same.

In these drawings: v Figure I is a perspective view showing .the

1 luminaire from underneath;

Figure 2 is a perspectiveview showing anumber of luminaires employed for lighting a row of counters and shelvin Figure 3311s a transverse vertical sectional view through the luminaire, parts being in elevation;

Figure 5 is an inverted nalre; and

Figure 6 is a chart showing light distributions along and acrossthe working area.

In the drawings, a light source in the form of a concentrated filament incandescent lamp is illustrated at ID, the light'center being at L. C. I

A spherical reflector H is placed above the lamp. The output of the lamp is received by an upper dished lens I2, having annular prisms l3 adapted to receive the widely divergent light rays I! and reduce their convergence, as indicated at I5, so

that they appear to come from a virtual light source 1. c. a substantial distance above the real light source L. C.

The lens i2 is normally in the form of a piece of pressed glass and has downwardly extending flanges I6, which may conveniently provide a square contour. The upper lens part I2 is secured to a lower lens part ll by clips 18. This lower lens part has an upper peripheral flange l9 adapted to fit against the depending flanges it of the upper lens part and to support the lenssystem in a box or housing. Thelower lens part H has two downwardly extending side walls 20, 20 provided with light depressing prisms 2| and these side walls are interconnected by a fiat, or

, substantially flat, bottom portion 22 having parallel prisms 23. The ends of the lower refractor, or lens part, are curved upwardly as indicated at 24, Figure 4, and the parallel prisms 23 extend up along these ends, as will be apparent from Figures 1 and 3.

The luminaire may be mounted in-an exposed box, such as indicated at 25 of Figure 1, or the luminaire, except for the lower lens part, may be recessed in the ceiling, asindicated in-Figure 2.

The prism system on theflat portion and ends of the lower refractor part is designed to accept the moderately divergent light rays I5 and transmit them at slight angles to the vertical, asindicated at 26 in Figures2 and 3. These rays ,diverge in longitudinal planes, as shown inFigures 2 and 4, continue in the same, or nearly the same, direction, depending upon whether, or not the central area of the bottom refractor is 'pro-' .vided with shallow prisms .21. These act to slightly diverge the rays which would normally be emitted more nearly vertical. Theseprisms 2'! reduce the maximum beam candlepower but ar efiectivevto alter the light distribution. so

' that a wider spacing of the light units may be Figure 4 is a longitudinal sectional view 1 had with reasonably uniform distribution of light between the units than where they are omitted. When the units are installed, as indicated in plan view of the lumi- Figure 2, above a row counters, it is possible to project a very intense beam at slight angles to the vertical, so as to illuminate the counter, and the higher angled spilled light- 28 on the inner side of the unit will be directed toward the shelving.

In Figure 6 the full line curves 30 and 3| show thedistribution along the counter in the plane ot maximum candlepower and the distribution across the counter tor a unit such as above illustrated employing a 200 watt lamp and wherein the light spreading prisms 21 are omitted. The curves 32 and 33, shown in broken lines illustrate the distribution of the same equipment, except that the prisms 21 are present.

It will be apparent that as far as light control and distribution is concerned, the lower retractor acts on the divergent light rays l5 as though they came from a source at the elevation l. c. Similar distribution or light (but at less intensity) could therefore be obtainedit the light source (with or without a spherical reflector) were mounted at the height corresponding to the virtual light source, and in this case the dished lens 12 could be omitted. Such a system would of course not be as efiicient in the utilization of the output ot the lamp tor count'er illumination as the compact arrangement illustrated, but would make it possible to employ the lower lens part in a unit designed to utilizethe light not controllable by the reflector and lower lens part as, for example, in an exposed unit having illuminated side walls or where the upper component was used for indirect lighting.

Since it is obvious that the invention may be embodied in other forms and constructions with in the scope of the claims, we wish it to be understood that the particular torm shown is but-one of these forms, and various modifications and changes being possible, we do not otherwise limit ourselves in any way with respect thereto.

We claim:

1. In a luminaire, means for acting on a downwardly divergent cone of light whose axis is vertical to convert it into a beam wherein the rays have substantially unchanged divergence in one direction and a substantially unitorm inclination to the vertical in transverse planes, comprising a horizontal lens intercepting said conical beam and having parallel prisms disposed in the direction of unchanged divergence, all the prisms to one side ot a vertical .plane through the apex of the cone and parallel with the prisms having a retracting power uniformly greater than that of those on the other side and such that the emitted light is directed across the said vertical plane at an angle to said' plane equal to, the angle'the light emitted by the prisms ot the said other side makes with said vertical plane.

2. A luminaire such as claimed in claim 1, wherein the said lens forms the bottom of a substantially square bowl, and the bowl has two substantially vertical side walls parallel with the prisms and end walls extending up to the same level as the side walls and along which the prisms extend.

3. A retracting bowl for direct lighting luminaires, the bowl having a rectangular configuration in horizontal planes, and being of chan-' nel shaped configuration in transverse vertical planes, and ot a shallow U-shaped configuration in longitudinal, vertical planes and having a fiat bottom, the bowl being provided with means tor producing a generally rectangular area of intense illumination in a region under the bowl and slightly displaced trom said vertical axis, said means comprising external parallel prisms extending lengthwise ot the channel bottom and up the ends of the U, the prisms having a configuration to direct a moderately divergent beam symmetrical about a vertical axis into an emergent beam in which the rays have substantially unitorm inclinations in planes transverse ot the prisms and diverge in lateral planes.

4. A luminaire comprising a light source, and a two part lens system below the source, the upper part including a dished central portion adapted to accommodate the source and having annular prisms about the vertical axis through the source for converging the light from said source into a beam diverging about said vertical plane at a slight angle, and with a system of parallel prisms on the other side of said vertical plane and of lesser retracting power to direct the light emitted thereby at the same angle of inclination to the vertical plane, so as to produce a generally rectangular area of intense illumination in a region under the luminaire and slightly displaced from said vertical axis.

5. A luminaire such as claimed in claim 4, wherein the lower part has two parallel, substantially vertical walls provided with horizontal light depressing prisms.

6. A luminaire such as claimed in claim 4, wherein the lower part has two vertical walls parallel with the lower prisms, and a flat bottom and upwardly sweeping end walls between the side walls and traversed by the parallel prisms.

7. A luminaire such as claimed in claim v-i, whereinthe bottom part has shallow prisms transverse ot the first mentioned prisms to slightly alter the divergence of the rays in said lateral planes.

8. A luminaire comprising a light source and a two part lens system underneath the source, the upper part including a dished central portion adapted to accommodate the source and provided with prisms to concentrate light received thereby into a beam diverging about a vertical axis, and peripheral downwardly extending flanges terminating a substantial distance above the bottom of the central portion and of substantially square contour, the lower part including two parallel side walls extending downwardly from two opposite flanges ot the upper part, and a bottom, interconnecting the side walls and the other two flanges, and having prisms parallel with the said side walls to accept divergent rays from the central portion of the upper part and retract them into a beam in which the rays have substantially uniform inclinations in transverse planes across said second mentioned prisms, the side walls receiving light transmitted through the opposed outer parts of the dished upper part and having light depressing prisms to lower said light rays.

THOMAS W. ROLPH.

KURT FRANCK. 

